Application of Quantum Annealing to Structural Modeling of Solid Solutions and Disordered Systems

Atomic substitutions, such as alloying or doping with cations, anions, and vacancies, are commonly used to tune material properties. First-principles calculations of these solid solutions and disordered systems require the preparation of structural models where atomic sites in the parent crystal are partially substituted. However, the number of possible atomic substitution combinations can grow exponentially, reaching billions or even trillions in some cases.

To address this, a strategy to significantly reduce the number of candidate structures is employed by using the Ewald energy, which can be calculated relatively quickly, for prescreening. The key aspect is the ability to evaluate the Ewald energy at ultrahigh speeds. Crucially, we focused on the fact that only the relative relation [larger or smaller] of the Ewald energies matters, rather than their accurate values.

Based on this insight, we have developed a Hamiltonian for quantum annealing that models the relationships between Ewald energies. We are now investigating the feasibility of using this approach for high-speed evaluation, aiming to streamline the screening process for large-scale structural modeling of disordered systems.